Dav Pilkey 
Ricky Ricotta’s Mighty Robot vs The Naughty Night-Crawlers from Neptune [EPUB ebook] 

From the creator of CAPTAIN UNDERPANTS, comes a BRAND NEW out-of-this-world friendship adventure – now in full colour! Having a Mighty Robot as a best friend is great, but it’s even greater when he can help build a fort! After some pounding, some banging, and some laser eye-welding, Ricky and his Mighty Robot build the coolest fort ever! But when Ricky’s cousin Lucy shows up, she renames the fort a "castle" and says it needs curtains – rats! But these are the least of Ricky’s worries. . . Nimrod Night Crawler has created a wormhole so he can send his army of evil Night Crawlers to help him take over the world, and Ricky’s Robot is trapped in a deep pit! Without his Mighty Robot, it’s up to Ricky – and an unlikely hero – to put a stop to this nightmare from Neptune!